The present invention relates to a support element for a wiper strip which is a part of a wiper blade for windshields of motor vehicles, and a method for producing it.
Support elements of this type should ensure that the force with which the wiper arm connected with the support element is pressed against the windshield is distributed as uniformly as possible. Due to a corresponding curvature of the support element when not under load--that is, when the wiper blade rests against the windshield--the ends of the wiper strip which rests in its entirety against the windshield during operation of the wiper blade are loaded toward the windshield by the support element which is tensioned in this case, even though the radii of curvature of spherically curved vehicle windshields changes with every position of the wiper blade. The curvature of the support element, and therefore the curvature of the wiper blade, must accordingly be somewhat greater that the greatest curvature measured in the wiping field of the windshield to be wiped. The support element therefore replaces the complicated support clip construction with two spring rails which are arranged in the wiper strip according to practice in conventional wiper blades.
A known support element of this type (EP 0 498 802 B1) has an elongated core piece which is rectangular in cross section and made of wood, foamed material, or the like, so that the transverse forces acting on the wiper blade during the wiping operation can be absorbed without disadvantageous deformation of the wiper blade. It is relatively complicated to produce the support element and, therefore, the wiper blade because the core piece must be packed all around by nonwoven or formed fabric strips.